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Exchange Team Blog
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No Exchange Server Security Updates for April 2026

The_Exchange_Team's avatar
The_Exchange_Team
Platinum Contributor
Apr 14, 2026

Although Exchange 2016 and 2019 are now out of support, some customers have purchased the Exchange 2016 and 2019 Extended Security Update (ESU). We have therefore decided that until the end of this Exchange 2016 and 2019 ESU period (April 2026) we will make an explicit update related announcement even if we DO NOT release anything for that particular month.

There are no security releases for any version of Exchange Server in April 2026, for customers with Exchange SE, or Exchange 2016 or 2019 ESU.

Please keep upgrading your organizations to Exchange SE.

The Exchange Team

Published Apr 14, 2026
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exchange 2016
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9 Comments

  • alex kim's avatar
    alex kim
    Copper Contributor
    Apr 20, 2026

    I just want to report something weird happened,

    I have Server 2022 DCs that are not patched yet, and 3x Exchange SE installed on Server 2019.

    After installing KB5082123 and KB5084066 to 2 of the nodes and rebooted one at a time, outlook autodiscover, OWA and ECP could not be connected. Outlook could not connect to exchange. Once uninstalled both KBs the operation came back to normal.

    Anyone experienced the similar issues?

    • alex kim's avatar
      alex kim
      Copper Contributor
      Apr 21, 2026

      Found what the problem was after applying patch and rebooted, startied to see "An error occurred while using SSL configuration for endpoint 0.0.0.0:444.  The error status code is contained within the returned data." error, it is a system error and event ID is 15021.

      All Exchange Back End site's Binding for https port 444was "Not selected" changed it to "Microsoft Exchange" fixed the issue.

      • alex kim's avatar
        alex kim
        Copper Contributor
        Apr 21, 2026

        It seems others had similar issues, https://www.reddit.com/r/exchangeserver/comments/1qfoelu/exchange_2019_not_working_when_2019_dc_was_patched/

        https://martinsblog.dk/exchange-an-error-occurred-while-using-ssl-configuration-for-endpoint-0-0-0-0444/

        In my case resetting IIS did not fix the issue also when we attempted IIS reset we got we don't have permission to reset IIS error.

  • wroot's avatar
    wroot
    Silver Contributor
    Apr 14, 2026

    This is the last such announcement, right?

    • Nino_Bilic's avatar
      Nino_Bilic
      Icon for Microsoft rankMicrosoft
      Apr 14, 2026

      I mean the ESU period is ending... but we might still do announcements when there are no releases.

      • ITSystemsMSP's avatar
        ITSystemsMSP
        Copper Contributor
        Apr 14, 2026

        I think it's very helpful to know we're not waiting for a post to say there are updates - the clarity that there are no updates is the best no-update update!